Oil Excess Venting Level


Are you aware of any confirmed cases of this Bg109 actually working in our Cirrus engines and is it approved as an acceptable additive?

I tend to see this as another version of the famous “ring flush” cocktail that has very mixed results.

I will not address “approved.” I will only say that the BG folks see no reason it would not work in aircraft engines and that there is nothing in it that might hurt an engine if used properly. The difference between BG109 and other ring flush methods is that proper use of BG109 involves operating at temperature (high idle - say 1200 RPM) for 10-20 minutes followed by an immediate oil change. BG109 will clean crud and that crud should be drained right away.

Maybe bullshit in a bottle, but maybe not. The automotive and diesel folks seem to only have good things to say about it.

As for lead salt deposits being different than carbon… this is true, but it may be a case of washing out the baby with the bath water.

For an engine with stuck rings, it won’t hurt anything, but might help. For engines on the way to stuck rings… perhaps a few prophylactic treatments, about at mag IRAN frequency, might be helpful in keeping ring glands clean(er).

I’d love to have someone with stuck rings try it and report back.

Agreed, but it probably won’t be me. I tend to be very conservative and if it is not approved for aircraft engine use, I’m not inclined to bet my life & property on it.

I’m arguably too anal, but something like this chemical mix that purportedly can break down bonded junk from within the piston ring groves in 20 minutes or so, just might have other unintended consequences.

As a for example, most of us have a quick oil drain on the bottom of our oil pans. These have two rubber o-rings within its spring loaded assembly that is the only thing that stops all of the engine’s oil from departing the engine. Is the BG chemical mix hostile enough to break down that o-ring? If so, how long will that process take with hot oil?

Food for thought while on a cross country.


I’m neither an A&P or an organic chemist but the inside of an engine is moderately nasty chemical environment to begin with given that it’s hot, full of solvents and oils, and all kinds of side products of combustion. The active ingredient of BG109 appears to be cyclohexanone which doesn’t at first glance to have any unique affinity to eat plastics or rubbers, though I certainly wouldn’t toss a can in my engine either without a pretty trusted and experienced A&P in the loop.

Your question reminds me of one of my favorite odd posts on the Internet, written by a chemist who works in pharmaceuticals and has a great knack for storytelling.

In a comment to my post on putting out fires last week, one commenter mentioned the utility of the good old sand bucket, and wondered if there was anything that would go on to set the sand on fire. Thanks to a note from reader Robert L., I can report that there is indeed such a reagent: chlorine trifluoride.

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